Yep, here is what I do. Note: I have the title of each of my db connections as username@sid (i.e. scott@orcl)
Then I use the URL feature of Keepass with the following command...
cmd://"C:\Program Files (x86)\PLSQL Developer 12\plsqldev.exe" userid={T-REPLACE-RX:!{title}!@!/{password}@!}
if you were to have a single user per database you could also do this. Note: database would have to be in the title field.
cmd://"C:\Program Files (x86)\PLSQL Developer 12\plsqldev.exe" userid={username}/{password}@{title}